mod_invites_page: Fix templates including stray inviter name (thanks Menel) The util.interpolation syntax `{var?placeholder}` appears to have been intended as an if-not, but this syntax will always return either the variable or the placeholder-template.

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.